1. Field of the Invention
This invention relates to particulate polybutadiene crosslinked materials and a process of making the same. The particulate crosslinked product of the invention finds extensive application as blends with resinous materials used in machineries and electronics industries, as solid lubricating agents added to greases and lubricating oils, as anti-friction improvers for paints and inks and further as cosmetics blends.
2. Prior Art
Polybutadiene crosslinked particles are widely recognized for their high strength, high thermal resistance, low dielectric constant and low moisture-absorption characteristics, and are usually made available by mechanically pulverizing their initial massive crosslinked material.
However, such crosslinked particles are susceptible to discoloration upon exposure to ultraviolet rays and hence find limited commercial application. They are not suitable for outdoor application as they undergo abrupt discoloration from white to brown when exposed to sunlight. Mechanical pulverization of a massive or cloddish polybutadiene crosslinked material involves a difficulty in removing polymerization heat generated during its preparation and further in obtaining uniformly minute and regularly shaped particles at high yield. Emulsification crosslinking methods are also known and effective in so far as concerns the removal of polymerization heat, but not satisfactory in that the particles are liable to become coagulated or cohesive during crosslinking and fail to grow sufficiently minute.